Added flag in chrome://flags to enable the New Launcher UI.

ui/app_list/app_list_switches.h

Index: ui/app_list/app_list_switches.h
diff --git a/ui/app_list/app_list_switches.h b/ui/app_list/app_list_switches.h
index 487d84d77828bfa84a702c475da364bc88356c6f..f2d5aafc8debb4294faed43ab356966b7257ad18 100644
--- a/ui/app_list/app_list_switches.h
+++ b/ui/app_list/app_list_switches.h
@@ -15,6 +15,7 @@ namespace switches {
 APP_LIST_EXPORT extern const char kCustomLauncherPage[];
 APP_LIST_EXPORT extern const char kDisableAppListDismissOnBlur[];
 APP_LIST_EXPORT extern const char kEnableAppList[];
+APP_LIST_EXPORT extern const char kEnableNewAppListUI[];
 APP_LIST_EXPORT extern const char kEnableSyncAppList[];
 APP_LIST_EXPORT extern const char kDisableSyncAppList[];
 APP_LIST_EXPORT extern const char kEnableDriveSearchInChromeLauncher[];
@@ -23,6 +24,8 @@ APP_LIST_EXPORT extern const char kResetAppListInstallState[];
 
 bool APP_LIST_EXPORT IsAppListSyncEnabled();
 
+bool APP_LIST_EXPORT IsNewAppListUIEnabled();
+
 bool APP_LIST_EXPORT IsFolderUIEnabled();
 
 bool APP_LIST_EXPORT IsVoiceSearchEnabled();